LIBRARY 

OF    THE 

UNIVERSITY  OF  CALIFORNIA. 


ClMS 


GENERAL  SPECIFICATIONS 


FOUNDATIONS  AND    SDBSTRDCTDRES 


HIGHWAY  AND  ELECTRIC  RAILWAY  BRIDGES, 


ILLUSTRATED. 
19O2. 

By  THEODORE  COOPER, 

Consulting  Engineer. 


By  THEODORE  COOPER,  M.  Am.  Soc.  0.  E. 

Specifications  for  Foundations  and  Substructures  01 

Highway  and  Electric  Railway  Bridges,  1902,  .  $1,00 

Specifications  for  Steel  Highway  and  Electric  Railway 

Bridges,  1901,  .  0,50 

Specifications  for  Steel  Railroad  Bridges,  1901,    .        .       0,50 


SENT  BY  MAIL,  POSTPAID,  ON  RECEIPT  OP  PRICE. 


FOR  SALE  BY 

THE  ENGINEERING  NEWS  PUBLISHING  COMPANY. 

22O  Broad-way,  Ne-w  York: 


PREFACE. 

Standard  specifications  for  the  superstructures  of  high- 
way  bridges,  giving  the  proper  loadings,  methods  of  pro- 
portioning and  character  of  workmanship  are  readily 
obtainable.  But  for  the  foundations  and  substructures  of 
such  bridges,  there  is  no  standard  practice  or  set  of  rules. 

The  author  has  herewith  endeavored  to  illustrate  the 
more  common  forms  of  substructures  and  foundations  suit- 
able for  highway  bridges  and  give  the  required  proportions 
for  all  ordinary  cases,  with  instructions  and  specifications 
for  their  construction. 

Standard  proportions  and  specifications  for  the  sub- 
structures of  highway  bridges  will  not  only  broaden  the 
competition  for  their  construction,  but  will  result  in  obtain- 
ing a  better  class  of  substructures  than  has  generally  been 
the  case  heretofore.  They  will  also  enable  in  many  cases 
the  local  artisans  to  proportion  and  build  the  same. 


The  author  excludes  from  consideration,  difficult  founda- 
tions in  deep  water  or  those  requiring  pneumatic  or  other 
special  appliances  or  works  of  such  expense  as  would 
demand  especial  study  of  the  conditions  to  determine  the 
best  or  most  economical  solution ;  also  city  bridges  and 
long  span  bridges,  where  a  higher  and  more  elaborate  class 
of  substructure  may  be  demanded  and  justified. 


117945 


Copyright  by  THEODORE  COOPER,  Consulting  Engineer, 
35  Broadway,  New  York. 


General  Specifications  for  Foundations 
and  Substructures 

OF 

Highway  and  Electric  Railway  Bridges. 


X. 
PRELIMINARY  FACTS. 

The  proper  determination  of  the  character  and  location 
ol  the  piers  and  abutments  for  a  bridge  at  any  particular 
locality  requires  a  careful  judgment,  based  upon  a  knowl- 
edge of  the  conditions  of  the  stream  during  its  varying 
stages  of  low  and  flood  water ;  the  action  of  the  ice  and 
flood  trash ;  the  liability  of  the  banks  and  bottom  to  scour ; 
the  character  of  the  bottom  as  to  its  bearing  capacity  and 
the  possible  presence  of  poorer  material  below  that  which 
is  visible  or  can  be  reached  by  ordinary  means  of  examina- 
tion. 

In  cases,  therefore,  where  the  local  knowledge  of  the 
river  and  the  material  of  its  banks  and  bottom  is  not  com- 
plete and  certain,  a  special  examination  should  be  made  by 
an  experienced  engineer. 

The  author  therefore  assumes  that  either  from  local 
knowledge  or  by  a  special  examination,  the  character  of  the 
bottom  upon  which  the  piers  and  abutments  are  to  rest  and 
the  action  of  the  stream  at  its  various  stages  are  known. 

For  any  particular  crossing,  the  best  arrangement  of 
spans  for  economy  in  first  cost  and  for  future  maintenance 
will  depend  upon  the  proper  placing  of  the  piers  and  abut- 
ments and  the  selection  of  the  kind  of  piers  best  suited  to 
the  conditions. 

In  many  cases  the  location  of  the  piers  and  the  length  of 
the  spans  are  determined  by  the  natural  conditions  of  the 


banks  and  bottom  or  by  the  necessities  of  the  waterway,  for 
the  navigation  of  boats  or  rafts  or  on  account  of  flood  trash 
or  ice  floes. 

In  cases  where  there  is  liberty  to  select  such  spans  as 
may  be  most  economical  for  the  situation,  Appendix  A  will 
give  the  method  by  which  the  economical  arrangement  of 
spans  may  be  determined. 

CHARACTER  OF  THE  BOTTOM. 

1.  The  material   of   the   bottom    upon    which  piers  and 
abutments  must  be  founded  may,  for  the  purpose  of  these 
specifications,  be  divided  into  the  following  general  classes: 

Rock. 

Hard  ground,  as  hard-pan,  gravel,  compact  sand  or  hard 
dry  clay. 

Soft  ground,  as  soft  or  wet  clay,  silt  or  mud,  whose 
sustaining  power  must  largely  depend  upon  the  frictional 
resistance  of  long  piles  or  piles  driven  through  the  soft 
material  to  an  underlying  material  of  a  harder  character. 

PREPARATION  OF  FOUNDATIONS. 

First.  Where  they  are  above  the  water  or  where  the 
water  can  be  excluded  or  diverted  by  earth  or  timber  dams 
(Plate  I,  Fig.  i). 

2.  Rock. — The  site    of  the  pier  should  be  cleared  of  all 
the  over-lying  soil  and  other  material,  all  the  loose  and  dis- 
integrated portions  of  the   rock   removed  and  where  the 
surface  of  the  rock  is  inclined,  it  should  be  leveled  in  steps  to 
prevent  any  tendency  of  the  piers  to  slip  ;  all  irregularities 
of  the  surface  should  be  leveled  up  for  starting  the  masonry, 
by  filling  them  with  concrete. 

3.  Hard  Ground. — The  material  should  be  excavated  to 
a  depth  below  the  action  of  frost  or  scour  by  surface  cur- 
rents,   with    a    minimum  depth  of    3   feet,   if    above    the 
water.     And  for  foundations  in  the  water,  to  a  depth  suffi- 
cient to  be  below  any  possible  scour  by  the  river  currents 
(usually  increased  by  the  placing  of  piers  in  the  stream)  and 
to  give  the  piers  sufficient  foothold  to  resist  displacement 
by  the  shoving  action  of  floods,  ice  or  floating  material. 

4.  Where  the  foundations  are  on  or  near  the  banks  of 


streams  or  on  sloping  strata  they  should  be  carried  deep 
enough  to  ensure  them  from  slipping  by  the  sliding  of  this 
underlying  material. 

5.  Where  the  material  is  liable  to  be  softened,  scoured 
or   undermined    by    water   action   or  where   under  water 
the  foundations  cannot   be  carried    deep  enough  to  be  be- 
yond any  possibility  of  being  affected  by  scour  the  bottom 
should  be  piled. 

6.  Soft  Ground. — The  material  should  be  excavated  to  a 
stratum  of  harder  material  or  else  it  must  be  excavated  to 
a  depth  where  the  soil  is  permanently  wet,  if  on  land,  and 
below  possible  scour,  if  in   the  water.      Piles  spaced    not 
over  2-J  feet  centers  should  then  be  driven  over  the  whole 
area  to  a  "good  refusal."     The  piles  should  be  cut  off  or 
driven  to  one  level  and  then   covered  with  a  timber  plat- 
form or  a  layer  of  well- rammed  concrete  2  feet  thick,  upon 
which  to  start  the  masonry.     (See  Plate  i,  Fig.  i.) 

7.  In  all  cases  as  the   masonry  is  built  up,  the  remaining 
openings  of  the  excavation  should  be  refilled  with  good 
material  well  rammed  in  place. 

8.  Second.  Where  the  foundations  are  under  water  which 
cannot  be  readily  excluded  or  diverted  by  dams,  some  of 
the   special    methods   of    founding    hereinafter   described 
should  be  adopted. 

GENERAL  REQUIREMENTS. 

9.  No  piles,  timber  or  wood  shall  be  used  as  an  essential 
part  of  any  foundation,  above  the  water-line  or  in  ground 
which  is  not  permanently  wet. 

10.  No  iron  or  steel  cylinders,  beams,  columns  or  other 
forms  shall  be  used  in  direct  contact  with  any  kind  of  earth 
or  soil,  except  where  the  use  of  piers  with  metal  shells  in 
deep  water,  and  the  use  of  disk  or  screw  piles  may  be  justi- 
fied. 

11.  Wherever  possible,  all  concrete  and  masonry  must 
be  laid  in  the  open  and  not  deposited  through  the  water. 

12.  Preference  will  be  given  to  such  forms  and  methods 
of  founding  piers  as  do  not  require  the  concrete  to  be  de- 
posited through  the  water  or  the  use  of  metal  shells  per- 


6 

manently  exposed  to  oxydation  by  direct  contact  with  the 
water  and  mud. 

13.  The  tops  of  trestle  or  viaduct  piers  on  land  must  be 
at  least  18  inches  above  the  surface  of  the  ground. 

14.  Pedestal  stones  and  bridge  seats  must  be  single  stones 
or   concrete    blocks,   and   should    have   a   superficial   area 
double  of   that  of   the  metal  bearings  resting  upon  them, 
with  a  minimum  size  of  18  inches  square. 

15.  Where  required,  all  anchor  bolts  and  anchors  shall 
be  properly  placed  and  built  in  by  the  masonry  contractor, 
the  material  for  the  same  being  furnished  in   suitable  time 
by  the  contractor  for  the  metal  work. 

TIMBER  AND  PILES. 

16.  The  timber  and  piles  may  be   sound   pine,  spruce,, 
hemlock  or  other  woods  equally  good.     They  shall  be  free 
from  wind  shakes,  large  or  loose  knots,  decay,  worm  holes, 
or  other  defects  impairing  their  strength  or  durability. 

17.  The  piles  shall  be  at  least  6  inches  in  diameter  at  the 
small  end  and  not  less  than  10  inches  in  diameter  at  the  butt 
for  even  the  shortest  lengths.     They  shall  be  of  sufficient 
lengths  to  allow  being  driven  to  a  "good  refusal  "  under  a 
hammer  weighing  1,500  pounds  falling  freely  12  to  15  feet 
or  its  equivalent. 

18.  The    minimum    penetration    accepted   for   the   piles 
should  be  about  8  to  12  feet  in  wet  gravel,  sand  or  stiff  clay, 
and  20  to  40  feet  in  soft  clay  or  silt. 

19.  All  piles  in  each  foundation   must  be  driven  or  else 
cut  off  to  such  a  level,  that  no  wood,  including  the  plat- 
forms or  grillages,  will  be  above  the  permanent  water  line. 

SPIKES. 

20.  Spikes  for  underwater  platforms,  grillages  or  cribs 
need  not  be  headed,  but  may  be  cut  from  round  or  square 
bars   to  the   required   lengths   and  sufficiently  pointed  or 
sharpened  at  one  end  to  allow  their  being  driven  readily  ; 
when  the  timber  is  dry  or  hard  enough   to  require  boring 
for  the  spikes,  the  holes  must  be  bored  %  inch  less  than  the 
size  of  the  spikes.     The  length  of  the  spikes  must  be  suffi- 
cient to  pass  through  the  first  timber  or  timbers  and  enter 


the  last  one  at  least  6  inches  or  its  full  thickness.  The 
spikes  should  be  -^  square  or  ^  round  for  timbers  up  to  8 
inches  in  thickness  and  jj  square  or  £  round  for  timbers  12 
inches  and  over. 

NOTCHING  AND  DOVETAILING. 

21.  The  lateral  resistance  of  cribs  and  wooden  box  piers 
{§§  56,  86),  against  spreading  must  not  depend  solely  upon 
spiking  or  nailing,  but  shall  be  secured  by  proper  notching 
or  dovetailing  of  the  sticks  together. 

CEMENT. 

22.  The  cement  used  for  all  mortar,  concrete  or  masonry 
shall  be  an  accepted  and  established  brand  of  either  Natural 
or  Portland  cement.     It  must  be  in  good   condition,  per- 
fectly dry  and  free  from  lumpiness  and  must  be  protected 
from  moisture  till  used.     Small  pats  made  from  either  pure 
cement  or  from  a  mixture  of  cement  and  sand  in  equal  pro- 
portions must  set  under  water,  hard  and  strong  within  24 
hours,  be  of  a  uniform  color  and  show  no  signs  of  cracking 
or  swelling. 

SAND. 

23.  The  sand  used  for  all  mortar  and  concrete  shall  be 
hard,  clean,  coarse  and  sharp ;  it  must  be  free  from  parti- 
cles of  soft  stone,  earthy  or  alluvial  matter.    When  used  for 
mortar,  unless   free   from   pebbles   or  gravel,  it   must   be 
screened.     When  used  for  concrete  a  moderate  amount  of 
small  gravel  or  pebbles  may  be  permitted. 

CEMENT  MORTAR. 

24.  Cement  mortar  will  be  made  by  thoroughly  incorpo- 
rating the  cement  and  sand  in  the  following  proportions, 
viz.,  one  barrel  of  300  pounds  of    Natural  cement  and  12 
cubic  feet  of  sand,  or  one  barrel  of  375  pounds  of  Portland 
cement  and  16  cubic  feet  of  sand,  with  sufficient  water  to 
obtain  the  proper  consistency. 

GRAVEL  AND  BROKEN  STONE. 

25.  The  broken  stone  used  for  concrete  must  be  hard, 
tough  and  sound  stone,  free  from  all  dirt  and  earthy  matter 


8 

and  must  not  contain  any  stone  exceeding  2^-  inches  in  any 
dimension.  Clean  or  washed  gravel,  free  from  all  earthy 
matter,  may  be  used  instead  of  broken  stone  for  concrete 
without  screening.  But  an  allowance  must  be  made  in  the 
proportions  of  sand  to  be  added,  for  the  quantity  of  sand 
contained  in  the  unscreened  gravel. 

CONCRETE. 

26.  The  concrete  must  not  be  made  faster  than  it  can  be 
properly  placed    in   position.     It  shall  be  made  on  a  close 
board   platform.     The  materials   for   each    batch  must  be 
carefully  measured  to  ensure  the  correct  proportions.     The 
sand  and  cement  shall  be  evenly  spread  and  then  thoroughly 
mixed  by  turning  them   over  with  shovels  or  hoes,  before 
wetting ;  they  should  then  be  wetted  and   worked  to  a  soft 
mortar ;  then  the  proper  amount  of  broken  stone  or  gravel, 
previously   well  drenched  with   water,  should    be    spread 
over  the  mortar  and  well  incorporated  with  the  same  by 
turning  the  whole  over  at  least  twice  with  shovels  or  hoes. 
The  resulting  mixture  should  be  of  such  consistency  as  to 
quake  slightly  when    rammed,    but   not   before   ramming. 
All  concrete  as  soon  as  made  should  be  placed  in  position 
in  layers  about  6  to  8  inches  deep  and  thoroughly  rammed 
till  all  the  spaces  are  flushed  with  mortar. 

27.  If   the  mortar  does  not  flush  to  the  top  under  the 
ramming,  the  proportion  of  the  stone  must  be  reduced  till 
this  result   is   obtained.     On  the  contrary  if  the  material 
will  not  admit  of  proper  ramming,  being  too  quaky,  more 
stone  should  be  used  in  the  mixture. 

NATURAL    CEMENT   CONCRETE. 

28.  For   foundations  below  the   surface   of  the  ground 
where  the  concrete  will  not  be  exposed  to  the  action  of 
running  water  or  to  the  weather,  the    concrete   shall   be 
made   of  the   following  proportions:  For   each   barrel  of 
Natural  cement,  12  cubic  feet  of  sand  and  24  cubic  feet  of 
broken  stone  or  coarse  gravel. 

PORTLAND  CEMENT  CONCRETE. 

29.  For  monolithic  piers  and  abutments,  for  cylindrical 
and  wooden  box  piers  and  for  foundations  where  there  is  a 


liability  to  the  action  of  running  water  or  where  the  bottom 
is  soft  or  of  unequal  firmness,  the  concrete  shall  be  made  of 
the  following-  proportions  :  One  barrel  of  Portland  cement, 
10  cubic  feet  of  sand  and  20  cubic  feet  of  broken  stone  or 
coarse  gravel. 

30.  Pedestals   and    bridge   seats   may  be  made  of  con- 
crete containing  i   barrel  of  Portland  cement  to  8  feet  of 
sand  and   16  cubic  feet  of  broken  stone  or  coarse  gravel 
not  exceeding   three-quarters  of  an  inch   in   their  largest 
dimensions. 

ROCK-FACED    BROKEN-RANGE    MASONRY. 

31.  All  stone  must  be  sound,  durable,  and  suitable  in  form 
for  good  bonding.     All  stone  shall  be  laid  on  their  natural 
beds  and  be  rough  squared  on  the  joints,  beds  and  faces, 
breaking  joints  at  least  6  inches  and  with  at  least  one  header 
to   every  three  stretchers.     Headers  shall  be  at  least  3  feet 
long  or  extend  entirely  through  the  wall  and  be  at  least  15 
inches  in    width.     No  stone  shall  be  less  than  6  inches  in 
thickness   or  less  than    12  inches   on    the  least   horizontal 
dimension.     The    work    need    not   be    laid    up   in  regular 
courses,  but  shall  be  well  bonded  by  the  use  of  headers 
and  stretchers.      The  stone   shall  be   cleaned    and   damp- 
ened before  setting  and  shall  be  laid  in  Natural  or  Port- 
land cement  mortar,  as  per§  24.     The  joints  of  each  course 
must  be  completely  filled   with  cement  mortar  before  the 
succeeding   course   is    laid.     The  joints  must  not   exceed 
three-quarters  of  an  inch  in  thickness. 

32.  No  stone  less  than  12  inches  in  thickness  or  of  a  less 
superficial   area   than    12   square   feet  will  be   allowed  in 
foundation  footings,  cutwater  faces  or  the  coping. 

33.  The  bridge  seats  or  that  part  of  the  coping  which 
may  be  used  for  bridge  seats  shall  be  single  stones  not  less 
than    12  inches  thick  and  must  be  dressed  level  and  true 
on  the  upper  bearing  surface. 

ROCK-FACED    COURSED  MASONRY. 

34.  The  stone  shall  be  sound,  durable  and  of  an  accept- 
able character  for  the  locality.     All  stones  shall  be  laid  on 
their  natural  beds  in  regular  courses.     The  face  stones  shall 


10 

be  squared,  jointed  and  bedded  and  laid  in  regular  hori- 
zontal courses  of  not  less  than  10  inches  in  thickness,  de- 
creasing in  thickness  from  the  bottom  to  the  top  of  the 
work.  They  shall  consist  of  headers  and  stretchers  not 
less  than  3  feet  long  and  i£  feet  wide,  and  shall  have  a 
breadth  at  least  one  and  a  quarter  and  a  length  twice  the 
depth  of  the  course.  There  shall  be  one  header  to  every 
two  stretchers  and  these  shall  be  so  distributed  through- 
out each  course  and  in  alternate  courses  as  to  bond  the 
work  in  the  best  manner.  Each  stone  must  bond  with  the 
stones  of  the  underlying  course;  no  bond  of  less  than  9 
inches  will  be  allowed.  All  corners  and  batter  lines  must 
be  run  with  a  neat  chisel-draft  of  i^  inches  on  each  face 
and  the  projection  of  the  rock  face  must  not  exceed  3 
inches. 

35.  The  backing  shall  be  either  of  cement  concrete  or  of 
good-sized,  well-shaped   stones   laid  so  as  to  break  joints 
and  bond  the  work  in  all  directions. 

36.  The  whole  of  the  masonry  shall  be  laid  in  Natural 
or  Portland  cement  mortar,  as  per  §  24.  The  joints  of  each 
course  must  be  completely  filled  with  cement  mortar  before 
the  succeeding   course   is    laid.     The  mortar  joints  must 
not  exceed  three-quarters  of  an  inch  in  thickness. 

37.  The  footing  courses  shall  be  large  selected  stone  not 
less  than  15  inches  in  thickness,  nor  of  less  superficial  area 
than  15  square  feet. 

38.  The  coping  shall  be  large  selected  stone,  not  less  than 
15  inches  thick,  nor  of  less  thickness  than  the  thickness  of 
the  average  course  in  the  body  of  the  work.     The  tops  and 
faces  of    the    coping    shall    be    bush-hammered    and    the 
mortar  joints  throughout  must  not  exceed  3/8  inch. 

39.  Wing  walls  of  abutments  shall  be  capped  with  stone 
covering  the  full  width  and  not  less  than  6  inches  thick. 

40.  When  directed,  the  wing  walls  shall  be  stepped  and 
the  cap  stones  dressed  on  the  top  surface  and  faces. 

MONOLITHIC  CONCRETE  MASONRY. 

41.  These  should  be  built  within  suitable  molds,  to  the 
same   sizes,  forms   and  dimensions  as  for  other  classes  of 
masonry,  except  all  edges  and  corners  to  be  chamfered  and 
filleted  at  least  one  inch. 


11 

The  molds  should  be  built  of  plank  and  made  sufficiently 
rigid  to  be  practically  unyielding  under  the  ramming  and 
tamping  of  the  concrete.  The  sides  in  contact  with  the 
concrete  should  be  smooth  to  give  a  good  finishing  surface 
to  the  concrete.  The  concrete  must  be  of  unquestioned 
good  and  selected  materials  and  carefully  and  thoroughly 
mixed.  (As  the  strength  and  homogeneity  of  monolithic 
masonry  depends  upon  the  cement,  the  strength  and 
uniformity  of  all  the  cement  used  should  be  carefully 
tested  and  inspected  by  a  competent  person  to  see  that  it 
fully  comes  up  to  the  standard  requirements  of  the  best 
Portland  cement.)  The  concrete  should  be  deposited  in 
layers  of  6  to  8  inches  in  thickness  and  be  well  ram- 
med and  consolidated  before  adding  the  next  layer.  The 
portion  next  the  mold  must  be  well  cut  in  by  spades,  tamped 
and  flushed  to  secure  a  full  and  smooth  external  surface. 
Special  care  is  to  be  taken  to  insure  the  perfect  adhesion  of 
any  new  work,  after  the  previous  work  may  have  taken  a 
set,  by  roughening  the  old  work  by  picks  and  giving 
it  a  thorough  wetting  before  placing  additional  concrete. 

42.  Small    stones,    not   exceeding    one-man    stone,    well 
cleaned  and  thoroughly  wetted,  may  be  incorporated  into 
these  piers  in  the  following  manner  :  On  any  well-rammed 
layer  such  stone  may  be  bedded    in  mortar  composed  of 
i  part   of  Portland    cement   and  2\   of   sand  (i    barrel  of 
cement  to  10  cubic  feet  of  sand),  but  no  stones  are  to  be 
closer  together  or   to  the  molds   than   6   inches   or  f  the 
depth  of  the   adjacent  stones ;  the   spaces  are  then  to  be 
filled  with  well-rammed    concrete  ;  before  laying  another 
layer  of  stone,  the  previous  layer  of  stone  must  be  covered 
by  a  layer  of  concrete  of  sufficient  thickness  to  keep  the 
stones  in  adjacent  layers  at  least  6  inches  apart. 

43.  The  molds  must  not  be  removed  in  freezing  weather 
or  until  the  concrete  has  had  forty-eight  hours  with   the 
temperature  above  40  Fahr.  in  which  to  set.     The  masonry 
should  be  thoroughly  wetted  every  day  and  protected  from 
the  sun  until  at  least  one  week  after  its  completion. 

44.  After  removing  the  molds  the  external  surfaces,  if  not 
perfectly  full  and  smooth,  must  be  made  so  by  troweling 
with  cement  mortar  ;  the  top  surfaces  must  also  be  brought 
to  a  level  in  the  same  manner. 


12 

STEEL   SHELLS   FOR  CYLINDRICAL  OR 
OBLONG  PIERS. 

45.  The  plates  for  these  shells  shall  be  of  soft  or  medium 
steel.     For  all  parts  below  low- water  the  plates  shall  have 
a  minimum  thickness  of  f  of  an  inch,  except  where  the  out-- 
side is  protected  by  concrete  (Plate  7)  it  may  be  T5g-.     For 
parts  between  low  and  high  water  the  minimum  thickness 
shall  be  ^  of  an  inch.     For  parts  above  high  water,  £  of 
an  inch. 

46.  All  circumferential  seams  should  be  single  riveted, 
and  all  longitudinal  seams  double  riveted.     The  pitch  of 
the  rivets  shall  be  four  diameters  of  the  rivets  for  single 
riveting,   and  six  diameters  for  each  row  of   the   double 
riveting.     The  rivets  shall  be  £  or  f  inch. 

47.  The  shells  shall  be  thoroughly  painted,  both  inside 
and  out,  with  two  good  coats  of  red  lead  and  linseed  oil 
paint,  or  some  accepted  waterproof  preparation  of  acknowl- 
edged merit. 

48.  The  oblong  shells  shall  be  properly  and  effectively 
braced  against  distortion  by  either  the  water  pressure  or 
the  ramming  of  the  concrete  filling. 

49.  The  bracing  between  a  pair  of  cylindrical  shells  shall 
be  sufficient  to  meet  all  the  wind  forces  at  the  ends  of  the 
spans  resting  upon  them.     Where  such  braces  will  be  sub- 
jected to  the  blows  or  entangling  of  floating  materials,  they 
must  be  protected  by  plank  bulkheads  or  fenders. 

50.  The  material,  workmanship  and  proportions  of  such 
bracing  shall  be  in  accordance   with  Cooper's    Highway 
Bridge  specifications  of  1901. 


13 


GENERAL    DESCRIPTION 

OF 

SUBSTRUCTURES 

AND 

METHODS    OF    FOUNDING. 


TIMBER   PLATFORMS,   GRILLAGES,  CAISSONS 
AND  CRIBS. 

51.  To  spread  the  loads  and  weight  of  the  masonry  over 
soft  or  unequal  soil  or  to  facilitate  the  founding  of  piers 
under  water,  it  is  often  expedient  to  use  timber  platforms, 
grillages,  caissons  or  cribs* 

52.  Timber  platforms  consist  of  two  or  more  layers  of 
closely-laid   timbers   alternately   crossing  each   other  and 
thoroughly  spiked  together  to  act  as  a  solid  platform.    The 
thickness  and  size  of  each   platform  must  be  such  as  to 
distribute  in  a  proper  manner  the  full  load  over  the  piles, 
where    used,    or  over   the    underlying   material,    without 
exceeding  the  carrying  capacity  of  such  material. 

53.  Timber   grillages    are   similar   layers   of  alternately 
crossing  timbers  laid  with  open  spaces  about  the  width  of 
the  timbers,  so  they  can  be  weighted  with  gravel,  stone  or 
concrete,  to  facilitate  the  sinking  and  placing  into  position. 
They  are  generally  floored  top  and  bottom  with  plank. 

54.  Open   caissons,  the  only  kind  of  caissons  here  con- 
sidered, are  timber  platforms  or  grillages  with  water-tight 
wooden  sides  attached  thereto  (usually  so  as  to  be  remov- 
able after   the  work  is  complete),  so  as  to  form  a  water- 
tight box  in  which  the  masonry  can  be  built  in  the  dry; 
and  which  can  be  floated  into  place  and   sunk  in  proper 
position,  either  upon  the  pile  heads  or  on   the   prepared 
bottom  (Plate  I,  Fig.  2). 

55.  Timber  cribs  are   formed   of   alternate   longitudinal 
and    transverse   timbers,    notched,    dovetailed   and   spiked 
together  at  their  crossings,  so  as  to  form  a  rigid  structure 


14 

divided  into  a  series  of  pockets  several  feet  square.  The 
open  spaces  of  the  ends  and  sides  may  be  filled  in  with 
timber,  so  as  to  make  them  close  and  solid.  A  portion 
of  the  pockets  are  floored  over  so  they  can  be  filled  and 
loaded  with  broken  stone  or  concrete  to  sink  the  cribs  into 
position  upon  the  bottom  or  into  the  mud  to  a  depth 
sufficient  to  get  the  desired  stability.  After  the  crib 
is  in  proper  position  the  floored  pockets  should  be  loaded 
and  the  open  pockets  dredged  until  the  desired  depth 
is  obtained.  For  hard  bottom,  where  it  is  not  possible 
to  obtain  a  level  surface  by  dredging,  the  ground  should  be 
carefully  cross-sectioned  and  the  bottom  of  the  crib  built 
to  the  correct  shape  to  get  a  proper  bearing. 

56.  No  part  of  the  cribs,  grillages  or  platforms  must  ex- 
tepd  above  the  permanent  water-line. 

57.  Care  must  be  taken  that  the  upper  parts  of  the  cribs 
or  grillages  do  not  lift  free  from   the  loaded  bottoms  by 
buoyancy  of  the  water,  through  faulty  or  deficient  spiking. 

58.  After  the  cribs  are  sunk  into  position,  if  the  crib  is  to 
be  the  only  foundation  for  the  masonry  above,  the  open 
pockets  are  also  to  be  filled  with  stone  or  concrete. 

59.  Such  cribs  are  not  recommended  for  bridge  founda- 
tions, where  other  methods  can  be  employed.     But  where 
other  expedients  prove  too  difficult  or  expensive,  or  where 
the  bottom  is  of  such  a  character  that  cribs  may  be  placed 
without  possibility  of  their  future  settlement  or  displace- 
ment by  scour,  they  may  be  justified. 

60.  The  difficulties  attending  their  use  for  bridge  piers, 
unless  on  hard  bottoms,  even  when  well  and  substantially 
made,  are  (i)  their  further  settlement,  either  evenly  or  un- 
evenly, after  being  loaded,  thus  throwing  the  work  out  of 
line  and  level ;  (2)  their  greater  obstruction  to  the  river 
currents  and  hence  the  greater  liability  to  scour,  owing  to 
their  increased  size,  over  piers  of  more  solid  construction. 

61.  Cribs  for  bridge  piers  and  abutments  should  prefer- 
ably be  made  of  square  timber.     Round  timbers  do  not 
give  as  good  bearings  and  fastenings ;  round  timber  cribs, 
as  usually  constructed,  are  more  liable  to  distort  and  settle 
unequally,   and    also   offer   more   resistance   to   the   river 
currents. 


15 

62.  Cribs  may  sometimes  be  used  to  protect  and  hold  the 
footings  of  cylindrical   piers  on  hard  bottoms  as   will  be 
hereafter  described,   Plate   7  ;    or  to  give  lateral    stiffness 
to  pile  foundations  in  soft  mud  or  deep  water,  Plate  9. 

ABUTMENTS. 

63.  Abutments,  in  addition  to  supporting  the  bridge  and 
its  loads,  must  also  hold  back  and   protect  the  river  banks 
and  road  filling.     Generally  to  sustain  the  slopes  of  the 
banks  and  road  filling  and  protect  them  from  the  scouring 
action  of  the  currents,  wing  walls  will   be  needed  at  both 
the  upper  and  lower  sides  ;  their  most  favorable  inclination 
to  the  direction  of  the  stream  must  be  determined  by  the 
local  conditions.     In    some   cases   the  abutments    may  be 
placed  far  enough  back  into  the  banks  or  the  banks  may  be 
of  such  a  character,  that  no  wing  walls  will  be  needed.     In 
other  cases  it  may  be  sufficiently  satisfactory  to  protect  the 
banks  by  rip-rap,  paving  or  piles  sheathed  with  plank. 

64.  As  the  tendency  of  the  material  behind  an  abutment 
is  to  push  it  outward  or  to  overthrow  it  on  its  footing, 
which  would  be  greatly  increased  by  any  scour  along  or 
under  the  footing,  the  foundation  should  go  well  below  any 
possible  scour  and  be  of  a  width  sufficient  to  render  it 
stable  against  such  a  tendency. 

65.  Generally  abutments  should  be  of  stone  or  concrete 
masonry.     The  thickness  of  the  masonry  at  any  depth  below 
the  grade  of  the  roadway  should  be  four-tenths  of  such 
depth,  down  to  the  footing  courses. 

66.  The  footing  courses,  at  least  2   feet  thick,  either  of 
concrete  or  good  large  selected  stone  should   project   in 
front  two-thirds  of  their  thickness. 

67.  The   thickness   on    top   should   be  sufficient  for  the 
bridge  seats  and  a  back  wall  to  sustain  the  roadway  em- 
bankment.    The  coping  should  project  at   least  3    inches, 
but  not  more  than  one-third  of  its  thickness. 

68.  The  front  batter  should  be  i  in  12. 

69.  Provision   should   be  made,  especially  where    wing 
walls  are  used,  for  drainage  of  the  water  in  the  banks  behind 
the  walls,  by  weep  holes  or  other  means. 


16 

70.  As  the  masonry  progresses  the  back  filling  must  be 
replaced  and  consolidated  by  being  well  rammed  in  layers. 

71.  Plate  2  shows  an  abutment  without  wing  walls,  with 
the  governing  dimensions  for  bridges  of  different  spans  and 
widths.    Plate  3  shows  an  abutment  with  wing  walls.    (See 
§110). 

72.  Abutments  may  be  built  of   rock-faced  broken-range 
masonry,  rock-faced  coursed  masonry  or  monolithic  con- 
crete masonry  as  previously  described. 

73.  Where  the  foundation  cannot  be  carried  to  good  hard 
bottom  below  possible  scour,  the  bottom  should  be  piled 
with  piles  spaced  not  over  2|-  feet  centres,  cut  to  a  level; 
the  spaces  filled  in  with  broken  stone  and  the  whole  covered 
with  a  timber  platform  upon  which  to  start  the  masonry; 
all  the  timber  being  kept  below  low  water.     (See  §  6.) 

MASONRY  PIERS. 

74.  These    will   be   built   of    either  rock-faced   broken- 
range    masonry,  rock  faced    coursed    masonry    or    mono- 
lithic  concrete    masonry   as   previously    described.       The 
body  of  the  pier  shall  have  a  batter  of  i  in  24  at  the  ends 
and  at  the  sides.      The   coping    should    extend    at    least 
3   inches  all  around,    but   not  more   than  one-third  of  its 
thickness.     The  footing  courses  at  least  2  feet  thick,  either 
of  concrete  or  good   large   selected  stone,  should  extend 
two-thirds  of  their  thickness  all  around.      The  cut-water 
should  extend  3  feet  above  high  water  line. 

75.  Plate  4  gives  the  dimensions  for  such  a  pier  for  spans 
of  different  lengths  and  widths.     (See  §  no.) 

76.  These  piers  should   be  founded  below  any  possible 
scour  by  some  of  the  usual   expedients,  viz.,   excavating 
inside  of  earth  or  timber  coffer-dams,  or  sheet  piling,  or  by 
some  method  of  dredging.     Or  else  piles,  spaced  not  over 
2\  feet  centers,  should  be  driven   over  the  bottom  and  cut 
off  to  one  level  close  to  the  bottom  by  an  underwater  saw 
and  an  open  caisson  whose  bottom  is  a  properly  propor- 
tioned timber  platform  sunk  thereon,  and  the  masonry  laid 
up  therein  in  the  open  air. 


17 

DIAGONAL  PIERS. 

77.  In  quiet  waters  or  where  the  piers  will  not  be  sub- 
jected to  shocks  of  heavy  ice  or  floating  materials,  two  iso- 
lated piers  placed  diagonally  to  the  stream    may  sometimes 
be  substituted  with  advantage  for  a  single  pier. 

78.  Plate  5  shows  the  form  and  dimensions  of  such  piers. 

CONCRETE  PIERS  WITH  METAL  SHELLS. 

Plates  6,  7  and  8. 

79.  For  such  piers  either  one  oblong  shell  or  two  cylin- 
drical  shells  braced  together,  can  be  used. 

80.  For  soft  bottom  or  where  piles  can  readily  be  driven 
into  the  material  of  the  bottom,  the  shells  should  be  sunkinto 
the  ground  well  below  any  possible  scour,  by  weighting  the 
shells  and  excavating  the  material  from  the  inside.    The  in- 
closed space  should  then  be  filled  with  piles  of  such  lengths 
as  will  permit  driving  to  a  "  good  refusal,"  with  their  tops 
at  low  water  level.     The  piles  should  be  kept  free  from  the 
metal  shell  4  to  6  inches,  and  the  spaces  between  the  piles 
must  be  less  than  the  size  of  the  smallest  pile  used.  For  the 
oblong  shells  this  close  spacing  need  only  apply  to  the  end 
portions,  symmetrical  with  the  center  of  the  bearings  of  the 
trusses.   The  spaces  between  and  about  the  piles  must  then 
be  well  filled  and  rammed  with  Portland  cement  concrete. 
The  shells  above  low  water  shall  .then  be  pumped  dry  and 
filled    with    Portland    cement    concrete,    in    well-ramrned 
layers,  to  the  top,  where  it  must  be  finished  off  in  proper 
shape  for  the  bridge  seats  and  drainage. 

8 1.  For  material  which  can  be  excavated  from  the  inside 
of  shells  to  a  sufficient   depth   below   possible  scour,  but 
which  does  not  need  piling ;  the  shells  should  be  sunk  to 
the   proper   depth,  the    bottom   sealed  against  the  admis- 
sion of  water  by  depositing  concrete  through  pipes  or  in 
bags,  then  pumped  dry  and  the  interior  properly  filled  with 
Portland  cement  concrete.    Or,  the  bottom  may  be  dredged 
beforehand  to  a  proper  level  and  the  shells  bolted  rigidly 
to   timber  platforms  or   grillages   and   then  sunk  as  open 
caissons. 

82.  For  rock  bottom,  where  it  is  possible  to  fit  the  plat- 
forms to  the  rock  surface,  this  form  may  be  used,  but  where 


18 

the  weight  of  the  piers  is  not  sufficient  to  give  abundant 
security  against  the  shoving  action  of  floods,  ice  or  floating 
material  the  platforms  should  be  anchored  securely  to  the 
rock  by  anchor  bolts. 

83.  For   rock   or   hard    bottom    cylinder   piers   may  be 
steadied  and  also  protected  from  scour  by  a  surrounding 
crib,  as  shown  on   Plate  7.     After  the  crib  is  placed  and 
sunk  by  filling  the  floored  pockets  with  broken  stone  or 
concrete,  the  cylinders  should  be  lowered  into  place,  through 
the  open  pockets  provided  for  them  ;  then  the  open  spaces 
outside  of  the  cylinders  should   be  well  filled  and  rammed 
with  Portland   cement   concrete   to   the   full   depth  of  the 
crib.       Then    the    interior   of    the    cylinders    should    be 
pumped  dry  and  filled   in  the  usual  way   with   concrete. 
Where  the  crib  cannot  be  sunk  to  the  rock,  owing  to  the 
overlying   mud,    sheet   piles   or   sheeting   can    be    driven 
around  the  periphery  of  the  open  pockets  to  the  rock  and 
the    mud    removed,     before     placing     the     cylinders    or 
depositing  the  concrete. 

84.  The  permanency  of  the  wooden  crib  in  fresh  water 
and  the  protection  of  the  metal  shell,  both  outside  and  inside, 
by  cement  concrete  give  this  style  a  superiority  over  those 
where  the  outside  of  the  shell  is  in  direct  contact  with  the 
water  and  hence  subject  to  continuous  oxydation. 

85.  Little  or  no  faith  should  be  put  in  the  claim  that  when 
the  metal  shells  do  finally  rust  away,  the  concrete  core  will 
be  able  to  serve  the  full  purpose  of  a  pier,  even  for  the  best 
concrete  work;  and  when  the  concrete  is  deposited  through 
the  water  as  has  been  the  usual  custom  heretofore  it  will 
probably  be  found  to  be  no  better  than  loose  stone. 

WOODEN  BOX  PIERS. 

86.  In  many  localities  wooden  boxes,  as  shown  on  Plate 
10,  can  be  advantageously  substituted  for  the  metal  shells. 

87.  On   account  of   their   square   form,  they  should  be 
placed  diagonally  to  the  current.  The  timbers  being  entirely 
under  water,  will  be  permanent  in  fresh  water,  or  where  the 
waters  are  free  from  the  teredo  and  limnoria. 

88.  The  horizontal  sticks  should   be  notched  over  each 
other,  and  be  spiked  together  at  each  crossing  and  to  the 


19 

vertical  corner  sticks.  Horizontal  washboards  at  or  near 
the  level  of  the  ground  will  reduce  the  undercutting  ac- 
tion of  the  currents,  and  will  also  serve  for  loading  with 
stone  or  concrete  for  sinking  the  boxes  to  place.  It  may 
be  best  in  some  cases  to  make  the  exterior  flush  by  a  series 
of  vertical  timbers  spiked  to  the  horizontal  sticks. 

89.  For  soft  bottom  these  boxes  may  be  placed  in  position, 
weighted  and  then  sunk  by  excavating  the  interior  till  the 
proper  depth  is  obtained.     The  inner  space  should  then  be 
piled  and   filled  with  concrete    up    to   low    water    level  • 
above  that  stone  or  concrete  masonry  must  be  carried  up 
to  receive  the  superstructure.     In  some  cases  it  may  be 
best  to  drive  the  piles  or  at  least  a  few  of  them  first  and 
build  the  box  in  place  around  them. 

90.  For  hard  bottom  where  piles  cannot  be  driven,  a  simi- 
lar form  of  box  or  crib  can  be  secured  to  a  timber  platform 
or  grillage  and  sunk  as  an  open  caisson  upon  the  prepared 
bottom,  Fig.  2,  Plate  10. 

91.  The  upstream  corners  of  these  wooden  boxes  can, 
where  considered  desirable,  be  protected  with  an  angle  iron 
nose. 

TRESTLE  OR  VIADUCT  PIERS. 


PIERS  ON  LAND. 

92.  These  shall  be  built  of  stone  or  concrete  masonry 
and  capped  with  suitable  pedestal  stones  (§14). 

93.  For  gravel,   sand    or  good   hard   bottom    the    base 
area  of  the  piers  should  not  be  less  than  3^  feet  square  for 
spans  up  to  50  feet.     This  area  should  be  increased  50  per 
cent,  for  moderately  good  ground  and  the  bottom  piled,  if 
it  is  soft. 

94.  For  double-track    electric    railway    viaducts    these 
areas  should  be  doubled. 

95.  The  tops  of  such  piers  are  assumed  to  be  only  a  mod- 
erate height  above  the  ground  ;  if  it  is  found  desirable  to 
raise  them  considerably  above  the  ground,  the  sizes  must 
be  increased  accordingly,  for  a  proportional  strength. 

PIERS  IN  THE  WATER. 

96.  Any  of  the  previously  described  forms  and  kinds  of 
piers  for  use  in  water  may  be  used  for  trestle  piers. 


20 

97-  In  addition  disk  or  screw  piles,  with  shafts  or 
columns  of  solid  or  hollow  metal,  wrought  or  cast,  or  of 
wood,  may  be  used  for  this  purpose.  Below  the  mud 
line  the  shafts  should  preferably  be  of  cast  iron  or  timber. 

98.  The  disks  or  screws  must  be  of  sufficient  bearing 
area  to  support  the  loads  properly,  and  the  shafts  must  be 
considered  as  columns  for  their  unsupported  lengths  and 
be  proportioned  as  such.     And  in  case  of  screw  piles,  the 
shafts   and   the  fastenings  to  the  screw   must  be  propor- 
tioned to  resist  the  torsion  needed  to  force  the  screws  into 
the  ground. 

99.  Disk  Piles. — Plate  11.     These   are   used  where  the 
materials  of  the  bottom  can  be  penetrated  by  means  of  the 
water-jet.     The  disks  must  be  sunk  sufficiently  below  any 
possible  scour,  so  as  to  have  at  all  times  a  depth  in  the 
sand   of  6  to  10  feet.     For  silt  or  soft  material,  the  disks 
should  penetrate  to  a  good   stiff  bottom  or  else  to  a  depth 
such  as  would   be  required  for  good  piling  in  the  same 
material. 

100.  The  disks  shall  be  of  cast  iron  and  of  the  sizes  given 
in  the  tables  for  the  particular  span  as   proposed.     The 
thickness  of  the  metal  in  the  top  plate  and  thicker  parts  of 
the  cone  and   connecting  ribs  should   not  be  less  than  i£ 
inches  for  disks  24.  inches  diameter  or  i|-  inch  for  larger 
sizes.     The  cone  and  its  ribs  not  only  strengthen  the  disk, 
but  are  useful,  when  layers  of  clay  or  other  tough  mate- 
rial  occur,   to   aid    in    penetrating   them,  by  turning  and 
dropping  the  pile. 

101.  The  cone  should  have  a  tapered  interior  ending  in 
a  hole  large  enough   to  pass  freely  the  water  pipe,  which 
should  be  at  least  i^  inches  diameter. 

102.  The  shafts  or  columns  should    bear   squarely  and 
fully  upon  the  tops  of  the  disks  and  should  be  well  secured 
to  the  same. 

103.  Screw  Piles. — Plate  12.     Although  the   extra  cost 
of  the  screws  and  the  greater  difficulties  and  expense  of 
founding  screw  piles  render  their  use  in  most  cases  unde- 
sirable, cases  do  occur  where  their  use  is  justified. 

104.  As  experience  has  shown  that  in  sinking  such  piles, 
it  is  a  common  thing  to  call  into  play  the  full  torsional 


21 

capacity  of  the  shafts  at  times,  the  thickness  of  the  metal  of 
the  screws  and  all  the  connections  should  be  proportioned 
for  this  expectation. 

10$.  The  best  pitch  for  different  materials  is  a  matter  of 
experience  and  judgment.  In  general  it  should  be  from 
one-third  to  one-sixth  of  the  diameter  of  the  screw,  the 
larger  pitch  being  for  soft  material  and  decreased  as  the 
material  increases  in  toughness  of  penetration. 

106.  The  points  of  the  screws  may  be  made  of  various 
forms  to  suit  the  material,  which   is  to  be  penetrated,  viz., 
gimlet  pointed  for  gravel,  serrated  for  soft  rock  or  coral, 
blunt  for  sand  or  fitted  for  the  assistance  of  the   water-jet 
in  sand  or  gravel.     (See  different  forms  shown  on  Plate  12.) 

107.  Experiment  has  shown  that  for  driving  screw  piles 
with   disks  of  48  inches  diameter  into  chalk  rock,  gravel 
or  hard  bottom,  a  torsional  power  of   125,000  Ibs.  feet  was 
needed. 

TABLES  OF  SIZES  AND  DIMENSIONS. 

108.  In  order  to  render  the  plans  as  given  herein  of  more 
general  usefulness  the  author    has  omitted  all  data  as  to 
the  loads  allowed  in  different  cases,  and  such  other  data  as 
would  be  necessary  to  compute  and  design  the  substructures 
for  each  particular  case. 

He  has  considered  that  for  the  commoner  kinds  of  high- 
way and  electric  railway  bridges  it  would  be  better  to  de- 
termine the  proper  dimensions  for  the  various  cases  and 
present  them  in  a  tabular  form. 

He  believes  that  he  has  not  varied  from  what  is  con- 
sidered good  practice  in  the  pressures  used  for  good 
masonry,  or  the  classes  of  soils  considered  or  the  carrying 
capacity  of  piles,  screw  piles  or  disk  piles. 

SIZE  OF  PIERS  AND  ABUTMENTS. 

109.  The  dimensions  and  proportion  of  parts  shown  upon 
the  accompanying  plans  and  tables  for  piers  and  abutments 
of  different  kinds,  for  the  span  corresponding  to  that  of  the 
proposed  bridge,  shall  be  considered  the  minimum  sizes  to 
be  used  for  such  bridge. 


22 

no.  The  lengths  shown  on  Plates  2,  3  and  4  are  for  piers 
and  abutments  of  bridges  without  skew.  For  skew 
bridges  these  lengths  must  be  proportionally  increased. 

LOCATION  AND  LEVELS. 

in.  The  contractor  must  locate  the  foundations  and 
construct  the  substructures  at  the  exact  distances,  and  to  the 
correct  alignment  and  levels  required  for  the  proposed 
superstructure. 

PROPOSALS. 

112.  In  making  proposals  for  any  work  under  these 
specifications,  bidders  must  clearly  state  the  kind  of  sub- 
structure, character  of  the  masonry,  depths  of  the  founda- 
tions, length  and  kind  of  piles,  kind  of  cement  they  intend 
to  use,  and  such  other  facts  as  will  enable  a  fair  judgment 
and  comparison  of  the  several  bids. 


23 

APPENDIX  A. 

ECONOMICAL  NUMBER  OF  SPANS. 

The  total  cost  of  a  bridge  at  any  particular  crossing  must 
include  both  the  cost  of  the  superstructure  and  the  cost  of 
the  substructures  and  foundations.  One  additional  span, 
by  decreasing  the  length  of  the  spans,  decreases  the  cost  of 
the  superstructure,  but  by  adding  another  pier  increases  the 
cost  of  the  substructures.  Where  the  cost  of  an  additional 
pier  equals  the  saving  on  the  superstructure,  either  number 
of  spans  can  be  used  without  effecting  the  total  cost. 

In  order  to  have  a  ready  means  of  determining  the  proper 
number  of  spans  for  any  crossing,  where  the  local  conditions 
admit  of  a  choice,  the  diagram  on  Plate  13  has  been  pre- 
pared for  different  lengths  of  crossings  and  different  costs 
for  one  river  pier. 

To  provide  for  bridges  of  different  widths  the  cost  of  one 
pier  per  foot  of  clear  width'is  used;  the  clear  width  for  high- 
way bridges  being  the  width  of  roadway  and  sidewalks, 
and  for  electric  railway  bridges,  14  and  26  feet  for  single 
and  double  track  bridges. 

The  vertical  column  at  the  left  Jiand  of  the  diagram 
(scale  of  square  roots)  gives  varying  costs  per  foot  of  clear 
width  for  one  pier,  including  towers,  if  there  be  any. 

The  horizontal  line  at  the  bottom  gives  the  length  of  the 
crossings  between  centres  of  abutments  (one  scale  for  high- 
way and  one  for  electric  railway  bridges). 

Having  made  an  estimate  of  the  cost  of  one  pier  (see 
Appendix  B)  of  the  required  dimensions  as  per  the  speci- 
fications, divide  it  by  the  clear  width  of  the  proposed 
bridge.  Then  follow  the  horizontal  line  through  this  value 
to  the  vertical  line  through  the  length  of  the  crossing  and 
the  number  of  spans  given  for  that  point  will  be  the  required 
number  for  economy. 

Example:  Crossing,  500  feet;  width  of  roadway,  20  feet 
and  two  sidewalks,  each  5  feet. 
Should  one  pier  cost $900  or  $30  per  ft.  of  width,  use  /spans. 

"  $1,800"    $60  "     "    "      "      "    5     " 
"       "  $4,000  "  $133  "     "    "      "       "    3     " 


APPENDIX   B. 


TABLE  I. 
APPKOXIMATE.  CONTENTS  OF  ONE  MASONKY  PIEK.     PLATE  4. 

SEE  §  110. 


Spans. 

Roadways. 

DEPTH  OP  PIERS,  FEET. 

10 

15 

20 

25 

30 

100  ft                 •< 

12  feet... 

29 
38 
31 
50 

34 
46 
37 

58 

39 
53 
43 
66 

44 
61 
48 
73 

49 
68 
54 

80 

44 
59 
46 
75 

51 
70 
54 

86 

58 
80 
63 
99 

66 
91 
74 
109 

73 
101 
80 
120 

60 
82 
62 
102 

70 
95 
7i 
118 

80 
109 
86 
135 

90 
123 
98 
149 

100 
137 
109 
164 

77 
108 
80 
132 

90 
125 
96 
153 

103 
143 
112 

174 

116 
160 
127 
192 

130 
177 
142 
210 

94 
136 
100 
166 

111 
157 
120 
191 

128 
178 
140 
217 

145 
199 
159 
288 

162 

220 
178 
260 

20    "    

I 
150  ft  -! 

E,  single  T  

E,  double  T  

12  feet... 

20    "     

£00  ft                  -I 

E,  single  T  
E,  double  T  

12  feet... 

20    "    

250ft  •{ 

E,  single  T  

E,  double  T  

12  feet... 

20     "   

( 
800  ft.  .                -i 

E,  single  T  
E,  double  T  

12  feet.  .  . 

20     "   

E,  single  T  
E,  double  T  

Contents  in  cubic  yards.    Depth  of  pier  from  top  of  coping  to  bottom  of  footing. 

TABLE  II. 

APPKOXIMATE  CONTENTS  OF  ONE  MASONKY  ABUTMENT,  WITHOUT 
WING  WALLS.     PLATE  2. 

SEE  §  110. 


Spans. 

Roadways. 

DEPTH  OP  FOOTING  BELOW  GRADE,  FEET. 

10 

15 

20 

25 

30 

100  ft                 -I 

12  feet... 

20 
28 
21 
36 

22 
81 
25 
49 

39 
56 
44 

72 

45 
63 
50 

84 

67 
95 
75 
120 

77 
106 
85 
141 

100 
145 
112 
183 

116 
161 
128 
210 

145 

206 
160 
260 

165 

227 
181 
296 

20     "   

I 
800  ft         .        | 

E,  single  T  
E,  double  T  

12  feet... 

20     "   

E,  single  T  
E,  double  T  

Contents  in  cubic  yards. 


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Bridge  Foundations 

Plate  No.5. 

DIAGONAL 

MASONRYPIER. 


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Cooper  on  Highway 
Bridge  Foundations. 

P/cf+eNo.7. 
CYLINDER  PIE.R 

ON  ROCK 

wifhCrib  Protection. 

Dimensions  as  per 
Plate  No.  6. 


Cooper 

on 

H/qhway  Bridge 
Foundations. 

Plate  NaB. 

OBLONG 

STEEL  SHELL 
PIER. 


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Low  wafer. 


Cooper  on  Highway  Bridge  Foundations. 

Plate  No.9. 
CRIB  AND  PILE  FOUNDATION 

FOR  MASONRY  ORGYLINDER 


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Cooper  on  Highway 
Bridge  foundations. 

PlateNoJO. 
WOODEN  Box  FOUNDATION 

FOR  MASONRY  PIER. 


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100       ZOO      JOG      400       500       600       700       800       900       10*0 

Scale  for  Length  of  Crossing  for  Highway  Bridges.  (Feet) 


100      200     300     400      500     600      700     800      900     10 10 

Scale  for  Length  of  Grossing  for  Electric  Ry.  Bridges. 


Cooper  on  Highway  Bridge  Foundations. 

PlateNo.13. 
DIAGRAM  or  ECONOMICAL^SPANS. 


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